// Type definitions for Queue 4.5.1
// Project: https://github.com/jessetane/queue
// Definitions by: Alex Miller <https://github.com/codex->

import { EventEmitter } from "events";

export interface Options {
    /**
     * Max number of jobs the queue should process concurrently.
     *
     * @default Infinity
     */
    concurrency?: number;

    /**
     * Milliseconds to wait for a job to execute its callback.
     *
     * @default 0
     */
    timeout?: number;

    /**
     * Ensures the queue is always running if jobs are available. Useful in situations where you are using a queue only for concurrency control.
     *
     * @default false
     */
    autostart?: boolean;

    /**
     * An array to set job callback arguments on.
     *
     * @default null
     */
    results?: any[];
}

interface Queue extends EventEmitter {
    /**
     * Max number of jobs the queue should process concurrently.
     */
    concurrency: number;

    /**
     * Milliseconds to wait for a job to execute its callback.
     */
    timeout: number;

    /**
     * Ensures the queue is always running if jobs are available.
     */
    autostart: boolean;

    /**
     * An array to set job callback arguments on.
     */
    results: any[] | null;

    /**
     * Jobs pending + jobs to process.
     */
    readonly length: number;

    /**
     * Adds one or more elements to the end of the Queue and returns the new length of the Queue.
     *
     * @param workers New workers of the Queue.
     */
    push(...workers: QueueWorker[]): number;

    /**
     * Adds one or more elements to the front of the Queue and returns the new length of the Queue.
     *
     * @param workers Workers to insert at the start of the Queue.
     */
    unshift(...workers: QueueWorker[]): number;

    /**
     * Adds and/or removes elements from the queue.
     *
     * @param start The zero-based location in the Queue from which to start removing elements.
     * @param deleteCount The number of elements to remove.
     */
    splice(start: number, deleteCount?: number): Queue;

    /**
     * Adds and/or removes elements from the queue.
     *
     * @param start The zero-based location in the Queue from which to start removing elements.
     * @param deleteCount The number of elements to remove.
     * @param workers Workers to insert into the Queue in place of the deleted elements.
     */
    splice(start: number, deleteCount: number, ...workers: QueueWorker[]): Queue;

    /**
     * Removes the last element from the Queue and returns that element.
     */
    pop(): QueueWorker | undefined;

    /**
     * Removes the first element from the Queue and returns that element.
     */
    shift(): QueueWorker | undefined;

    /**
     * Extracts a section of the Queue and returns Queue.
     *
     * @param start The beginning of the specified portion of the Queue.
     * @param end The end of the specified portion of the Queue.
     */
    slice(start?: number, end?: number): Queue;

    /**
     * Reverses the order of the elements of the Queue in place.
     */
    reverse(): Queue;

    /**
     * Returns the first (least) index of an element within the Queue equal to the specified value, or -1 if none is found.
     *
     * @param searchElement The value to locate in the Queue.
     * @param fromIndex The Queue index at which to begin the search. If omitted, the search starts at index 0.
     */
    indexOf(searchElement: QueueWorker, fromIndex?: number): number;

    /**
     * Returns the last (greatest) index of an element within the Queue equal to the specified value, or -1 if none is found.
     *
     * @param searchElement The value to locate in the Queue.
     * @param fromIndex The Queue index at which to begin the search. If omitted, the search starts at the last index in the Queue.
     */
    lastIndexOf(searchElement: QueueWorker, fromIndex?: number): number;

    /**
     * Starts the queue.
     *
     * @param callback Callback to be called when the queue empties or when an error occurs.
     */
    start(callback?: (error?: Error) => void): void;

    /**
     * Stops the queue.
     */
    stop(): void;

    /**
     * Stop and empty the queue immediately.
     *
     * @param error error of why the stop has occurred, to be passed to start callback if supplied.
     */
    end(error?: Error): void;
}

interface QueueConstructor {
    (options?: Options): Queue;
    new (options?: Options): Queue;
}

declare const Queue: QueueConstructor;

export default Queue;

export interface QueueWorker {
    (callback?: QueueWorkerCallback): void;

    /**
     * Override queue timeout.
     */
    timeout?: number;
}

export interface QueueWorkerCallback {
    (error?: Error, data?: Object): void;
}